New technologies have emerged in the last few years that may
prove significant in the future. These technologies are
based on quantum mechanics, the fundamental laws that determine
how very small objects such as atoms and subatomic particles
behave. One of the most promising of these new technologies
is the atom laser, a source of coherent matter waves, that
is similar to the conventional laser, which is a source
of coherent light waves. The Space Atom Laser (SAL) is an
experiment proposed for a possible future flight in space, that will study
the physics of these novel devices. SAL will also use an atom laser to perform
studies in atomic optics, a field which attempts to manipulate
beams of atoms in ways similar to how conventional optics
are used to manipulate beams of light. In this specialized
field, atom opticians study how to make lenses, mirrors,
beam splitters and interferometers for atomic beams.

Quantum
mechanics states that all objects have both a wave nature
and a particle nature. At colder temperatures, the wave
nature becomes more evident. An atom laser works by cooling
a trapped dilute gas of atoms to a temperature so cold that
the atomic waves overlap. For certain types of atoms, the
gas will undergo a transition such that almost all the atoms
are in the exact same state, with the same wavelength. A
few atoms are allowed to leak out of the trap, forming the
output of the atom laser. This output shares many characteristics
with a laser beam: its bright (there are a lot of atoms
in the same state), its collimated (the atoms all go in
one direction, and don't spread out), and it is coherent
(the phase of the atom waves are all the same, so that is
the troughs and crests of the wave are all aligned). There
are differences however-the atoms move extremely slowly,
and they have mass, so they fall in gravity (gravity affects
light as well, but by an amount that is usually too small
to notice.)

Simple
atom lasers have been demonstrated in several of the leading
labs around the world. It has been predicted that they will
have a variety of uses, ranging from advanced atomic gyroscopes,
to lithography, where they might be used to produce advanced
microchips. However, many of these applications are hampered
by the fact that atom lasers are so sensitive to gravity.
It is predicted that in the microgravity of space the atomic
beam created with an atom laser will propagate like a true
laser beam, allowing some of these technological applications
to be proven.